The interworking between the 3GPP-based and non-3GPP-based networks, especially the interworking between the Long Term Evolution (LTE) and the evolved High Rate Packet Data (eHRPD) networks, is a hot topic among the standardization organizations. FIG. 1 illustrates the architecture for the interworking between the LTE and the eHRPD networks. As show in FIG. 1, two interfaces are added between the LTE and eHRPD networks: S101 and S103-U. S101 is an interface between a Mobility Management Entity (MME) and an evolved Access Network (eAN). It is essentially a tunnel for forwarding signaling messages between a terminal and a target network to help the terminal to pre-register with the target network or switch from a source network to a target network. S103-U is an interface between a Serving Gateway (S-GW) and a High Rate Packet Data Serving Gateway (HSGW). It is used to forward registration data stored in an LTE network to an eHRPD network, which then forwards the data to a terminal.
When a UE switches from an LTE network to an eHRPD network, the UE first needs to pre-register with the eHRPD network, namely, to establish a connection with the eHRPD network before accessing it, including negotiating an air interface session with the eAN, performing authentication, establishing a Point to Point Protocol (PPP) connection, and so on. In this way, the switchover delay can be greatly reduced. After determining to switch to the eHRPD network, the UE requests for the establishment of an air interface connection with the eAN. The eAN allocates an air interface resource for the UE, and sends a Traffic Channel Assignment (TCA) message to the UE. After that, the UE can switch from the LTE network to the eHRPD network based on the TCA message.
During implementation of the present invention, the inventor found that the following defect exists in the prior art:
An evolved NodeB (eNB) in the LTE network can be statically set with only one HRPD SectorID that corresponds to the eNB. In this way, the UE can establish a connection with the eAN in the eHRPD network that corresponds to the HRPD SectorID, and finally switches to the eHRPD network. However, because one eNB may be covered by a plurality of eHRPD sectors, the eAN in the handoff request sent by the UE may be different from the eAN statically set by the eNB. As a result, the handoff fails.